Home : Hardware Terms : CMOS Definition

CMOS

Stands for "Complementary Metal Oxide Semiconductor." It is a technology used to produce integrated circuits. CMOS circuits are found in several types of electronic components, including microprocessors, batteries, and digital camera image sensors.

The "MOS" in CMOS refers to the transistors in a CMOS component, called MOSFETs (metal oxide semiconductor field-effect transistors). The "metal" part of the name is a bit misleading, as modern MOSFETs often use polysilicon instead of aluminum as the conductive material. Each MOSFET includes two terminals ("source" and "drain") and a gate, which is insulated from the body of the transistor. When enough voltage is applied between the gate and body, electrons can flow between the source and drain terminals.

The "complimentary" part of CMOS refers to the two different types of semiconductors each transistor contains — N-type and P-type. N-type semiconductors have a greater concentration of electrons than holes, or places where an electron could exist. P-type semiconductors have a greater concentration of holes than electrons. These two semiconductors work together and may form logic gates based on how the circuit is designed.

CMOS Advantages

CMOS transistors are known for their efficient use of electrical power. They require no electrical current except when they are changing from one state to another. Additionally, the complimentary semiconductors work together to limit the output voltage. The result is a low-power design that gives off minimal heat. For this reason, CMOS transistors have replaced other previous designs (such as CCDs in camera sensors) and used in most modern processors.

NOTE: CMOS memory in a computer is a type of non-volatile RAM (NVRAM) that stores BIOS settings and date/time information.

Updated: May 25, 2017

Cite this definition:

https://techterms.com/definition/cmos

TechTerms - The Tech Terms Computer Dictionary

This page contains a technical definiton of CMOS. It explains in computing terminology what CMOS means and is one of many hardware terms in the TechTerms dictionary.

All definitions on the TechTerms website are written to be technically accurate but also easy to understand. If you find this CMOS definition to be helpful, you can reference it using the citation links above. If you think a term should be updated or added to the TechTerms dictionary, please email TechTerms!